Quantum Dot Nanoarrays: Self‐Assembly With Single‐Particle Control and Resolution

Abramson, Justin; Palma, Matteo; Wind, Shalom J.; Hone, James

doi:10.1002/adma.201104216

Cited by 34 publications

(38 citation statements)

References 74 publications

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“…Step changes of intensity have been used to determine the molecular occupancy of lipid vesicles 13 , monitor single QD blinking 47 , or DNA cleavage by a restriction enzyme 25 . Here the average bleaching step size was simply used to determine the single fluorophore intensity (see, e.g.…”

Section: Resultsmentioning

confidence: 99%

Improved Glass Surface Passivation for Single-Molecule Nanoarrays

Cai

Wind

2016

Langmuir

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Single-molecule fluorescence techniques provide a critical tool for probing biomolecular and cellular interactions with unprecedented resolution and precision. Unfortunately, many of these techniques are hindered by a common problem, namely the nonspecific adsorption of target biomolecules. This issue is mostly addressed by passivating the glass surfaces with a poly(ethylene glycol) (PEG) brush. This is effective only at low concentrations of the probe molecule, because there are defects inherent to polymer brushes formed on glass coverslips, due to the presence of surface impurities. Tween-20, a detergent, is a promising alternative that can improve surface passivation, but it is incompatible with living cells, and it also possesses limited selectivity for glass background over metallic nanoparticles, which are frequently used as anchors for the probe molecules. To address these issues, we have developed a more versatile method to improve the PEG passivation. A thin film of hydrogen silsesquioxane (HSQ) is spin-coated and thermally cured on glass coverslips in order to cover the surface impurities. This minimizes the formation of PEG defects and reduces nonspecific adsorption, resulting in an improvement comparable to Tween-20 treatment. This approach was applied to single-molecule nanoarrays of streptavidin bound to AuPd nanodots patterned by e-beam lithography (EBL). The fluorescence signal to background ratio (SBR) on HSQ coated glass was improved by ~ 4-fold as compared to PEG directly on glass. This improvement enables direct imaging of ordered arrays of single molecules anchored to lithographically patterned arrays of metallic nanodots.

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Section: Resultsmentioning

confidence: 99%

Improved Glass Surface Passivation for Single-Molecule Nanoarrays

Cai

Wind

2016

Langmuir

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“…Electron beam and other forms of lithography could be used to etch the surface of a suitable substrate [92][93][94]. Further opportunities might be afforded by quantum dot nanoarrays [95], especially given the possibility of forming anisotropic components with directional emission properties [96]. Lastly, since magnetic guidance proves amenable to maneuvering magnetizable nanoparticles, this too might afford a means of fulfilling the necessary symmetry conditions without the demands of intrinsic symmetry [97].…”

Section: Discussionmentioning

confidence: 99%

Direct generation of optical vortices

2014

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A detailed scheme is established for the direct generation of optical vortices, signifying light endowed with orbital angular momentum. In contrast to common techniques based on the tailored conversion of the wave front in a conventional beam, this method provides for the direct spontaneous emission of photons with the requisite field structure. This form of optical emission results directly from the electronic relaxation of a delocalized exciton state that is supported by a ringlike array of three or more nanoscale chromophores. An analysis of the conditions leads to a general formulation revealing a requirement for the array structure to adhere to one of a restricted set of permissible symmetry groups. It is shown that the coupling between chromophores within each array leads to an energy level splitting of the exciton structure, thus providing for a specific linking of exciton phase and emission wavelength. For emission, arrays conforming to one of the given point-group families' doubly degenerate excitons exhibit the specific phase characteristics necessary to support vortex emission. The highest order of exciton symmetry, corresponding to the maximum magnitude of electronic orbital angular momentum supported by the ring, provides for the most favored emission. The phase properties of the emission produced by the relaxation of such excitons are exhibited on plots which reveal the azimuthal phase progression around the ring, consistent with vortex emission. It is proven that emission of this kind produces electromagnetic fields that map with complete fidelity onto the phase structure of a Laguerre-Gaussian optical mode with the corresponding topological charge. The prospect of direct generation paves the way for practicable devices that need no longer rely on the modification of a conventional laser beam by a secondary optical element. Moreover, these principles hold promise for the development of a vortex laser, also based on nanoscale exciton decay, enabling the production of coherent radiation with a tailor-made helical wave front.

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“…[4][5][6]15,16 In order to simulate the IS structure as in Fig. 1, a new functionalization process was developed to bind biotinylated UCHT1 Fab on AuPd nanodots and modify the PEG passivation layer by introducing NTA groups to bind his-tag ICAM-1.…”

Section: Bifunctionalizationmentioning

confidence: 99%

Bifunctional nanoarrays for probing the immune response at the single-molecule level

Cai¹,

Depoil²,

Palma³

et al. 2013

Journal of Vacuum Science & Technology B, Nanotechnology an

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Bifunctional nanoarrays were created to simulate the immunological synapse and probe the T-cell immune response at the single-molecule level. Sub-5 nm AuPd nanodot arrays were fabricated using both e-beam and nanoimprint lithography. The nanoarrays were then functionalized by two costimulatory molecules: antibody UCHT1 Fab, which binds to the T-cell receptor (TCR) and activates the immune response, bound to metallic nanodots; and intercellular adhesion molecule-1, which enhances cell adhesion, on the surrounding area. Initial T-cell experiments show successful attachment and activation on the bifunctional nanoarrays. This nanoscale platform for singlemolecule control of TCR in living T-cells provides a new approach to explore how its geometric arrangement affects T-cell activation and behavior, with potential applications in immunotherapy. This platform also serves as a general model for single-molecule nanoarrays where more than one molecular species is required.

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Quantum Dot Nanoarrays: Self‐Assembly With Single‐Particle Control and Resolution

Cited by 34 publications

References 74 publications

Improved Glass Surface Passivation for Single-Molecule Nanoarrays

Improved Glass Surface Passivation for Single-Molecule Nanoarrays

Direct generation of optical vortices

Bifunctional nanoarrays for probing the immune response at the single-molecule level

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